Variable opening slide gate for regulating material flow into airstream

Abstract

Apparatus for delivering controlled amounts of granular resin into a conveying conduit includes a hopper for storing the resin, an air cylinder, a double-ended piston within the air cylinder, passive and active piston rods extending from opposite sides of the piston out of the ends of the cylinder, and a slide gate connected to the active piston rod, with the slide gate being positioned between a discharge opening of the hopper and an opening in the conveying conduit.

We claim the following: 
     
       1. Apparatus for continuously vertically delivering variably controlled amounts of granular resin material into a horizontal conduit carrying moving air for continuous pneumatic conveyance of the granular resin material, comprising:
 a) a hopper for storing the granular resin material, the hopper comprising a discharge opening leading vertically downwardly to an outlet at the hopper bottom for vertically downward flow of granular resin material out of the hopper a horizontal section of the pneumatic conveyance conduit, the outlet communicating with the horizontal section of the pneumatic conveyance conduit; 
 b) a horizontally oriented double ended air cylinder; 
 c) a piston within the air cylinder, the piston moving horizontally within the cylinder in response to differential pressures on either side of the piston; 
 d) a passive piston rod extending horizontally from a first side of the piston out of one end of the cylinder; 
 e) an active piston rod extending horizontally from a second side of the piston out of a second end of the cylinder; 
 f) the active and passive piston rods being of the same diameter and axially aligned; 
 g) a slide gate assembly comprising a housing and a horizontally and transversely elongated blade therewithin, the slide gate housing being connected to the hopper outlet intermediate the discharge opening and the horizontal section of the conveyance conduit; the slide gate housing having a vertical passageway therethrough aligned with the hopper outlet; the slide gate blade being connected to the active piston rod; the slide gate blade residing in the slide gate housing between the hopper discharge opening and the conduit and being movable horizontally within the housing responsively to the piston along a continuum of positions between a first extremity at which the slide gate housing vertical passageway is occluded by the slide gate blade so that no granular resin material can flow downward from the hopper outlet through the vertical passageway and a second extremity at which the slide gate housing vertical passageway is open and granular resin material can flow freely downwardly through the vertical passageway. 
 
     
     
       2. A method for continuously supplying controlled amounts of granular resin material to a horizontal section of a pneumatic conveyance conduit for continuous pneumatic conveyance of the granular resin material through the conduit, comprising:
 a) providing a hopper for storage of the granular resin material therein, the hopper having a discharge opening leading vertically downwardly to an outlet at the hopper bottom for gravity induced downward flow of granular resin material out of the hopper into the horizontal section of the pneumatic conveyance conduit; 
 b) providing a double ended cylinder; 
 c) positioning a piston within the cylinder, the piston being movable within the cylinder in response to differential pressure on either side of the piston; 
 d) pressurizing the cylinder with pressure on either side of the piston; 
 e) providing a first piston rod extending from one side of the piston slidably through an end of the cylinder facing the portion of the piston from which the passive piston rod extends; 
 f) providing a second piston rod extending from an opposite side of the piston slideably through a second end of the cylinder, the piston rods being of the same diameter and being axially aligned; 
 g) providing a slide gate assembly consisting of a slide gate housing and a slide gate blade positioned in the slide gate housing, the slide gate housing connecting to the hopper outlet intermediate the discharge opening and the conveyance conduit; the slide gate housing having a vertical passageway therethrough aligned with the hopper outlet, the slide gate blade being movable continuously between a piston position blocking downward granular resin material flow from the hopper outlet and a position removed from the hopper outlet thereby permitting downward granular resin material flow from the outlet; the slide gate blade residing slideably in the slide gate housing between the hopper discharge opening and the pneumatic conveyance conduit; 
 h) connecting the slide gate blade to one of the piston rods; 
 i) moving the piston by adjusting differential pressure thereon until the piston reaches a position resulting in the desired flow rate of granular resin material out of the hopper through the slide gate and into the conveyance conduit; and 
 j) regulating the flow of granular resin material in the conveyance conduit through adjusting position of the piston by adjusting differential pressure on the piston surfaces in response to feedback signals indicative of dynamic granular resin material flow in the conveyance conduit. 
 
     
     
       3. Apparatus for continuously delivering variably controlled amounts of granular resin material to a conduit for pneumatic conveyance of the granular resin material therethrough, comprising:
 a) a hopper for storing the granular resin material, having an outlet at the hopper bottom for downward flow of granular resin material downwardly out of the hopper into the conduit; 
 b) a supply of pressurized fluid; 
 c) an double ended cylinder; 
 d) a piston within the cylinder, the piston moving within the cylinder in response to differential pressure on either side of the piston; 
 e) first valves in the cylinder, one valve on either side of the piston, each connected to the fluid supply for furnishing pressurized fluid to the cylinder interior on opposite sides of the piston; 
 f) control valves in the cylinder, one control valve on either side of the piston, for exhausting pressurized fluid from the respective sides of the cylinder to atmosphere; 
 g) a first piston rod extending from a first side of the piston through one end of the cylinder; 
 h) a second piston rod extending from a second side of the piston through a second end of the cylinder; 
 i) the piston rods being of common diameter; 
 j) a slide gate having a housing and a flat, horizontally elongated blade therewithin, the slide gate connecting to the hopper and being positioned intermediate the hopper outlet and the conduit; the slide gate having a horizontal passageway therethrough aligned with the hopper outlet; the slide gate blade connecting with one of the piston rods, residing between the hopper outlet and the conduit, and being movable responsively to the piston to regulate the size of the passageway through the slide gate; and 
 k) a microprocessor connected to the first valves, to the control valves, and to at least one physical parameter sensor connected to the hopper, for regulating granular resin material flow out of the hopper, through the slide gate and into the conveying conduit by positioning the piston connected to the slide gate in response to differential pressure on the piston by adjusting the control valves to exhaust to atmosphere in response to signal from the sensor. 
 
     
     
       4. The method of  claim 2  where the differential pressures on the piston surfaces are adjusted by exhausting fluid from the cylinder. 
     
     
       5. The method of  claim 2  wherein the fluid is air. 
     
     
       6. The method of  claim 2  wherein the fluid is oil. 
     
     
       7. The method of  claim 3  wherein the physical parameter sensor is selected from the group consisting of flow sensors, granular material weight sensors, and vacuum level sensors. 
     
     
       8. A method for continuously supplying controlled amounts of granular resin material from a pneumatic conveyance conduit for pneumatic conveyance of the granular resin material through the conduit, comprising:
 a) providing a storage hopper having the granular resin material therein with a discharge opening at the hopper bottom for downward flow of granular resin material out of the hopper and a valve at the discharge opening for controlling downward granular resin material flow from the hopper; 
 b) providing a double ended air cylinder; 
 c) positioning a piston within the air cylinder, the piston being movable within the cylinder in response to differential pressure on either side of the piston; 
 d) providing piston rods extending from opposite sides of the piston slideably through opposite ends of the cylinder; 
 e) the piston rods being of the same diameter; 
 f) connecting the valve to one of the piston rods; 
 g) applying first differential pressures on either side of the piston; 
 h) moving the piston by adjusting differential first pressures thereon until the piston reaches a position resulting in the desired flow rate of granular resin material out of the hopper; 
 i) continuously regulating flow of granular resin material out of the hopper through continuously adjusting position of the piston by continuously adjusting differential pressures on the piston surfaces by exhausting fluid from the cylinder in response to at least one feedback signal indicative of condition of granular resin material flow out of the hopper. 
 
     
     
       9. In apparatus for delivering granular resin material vertically downwardly out of a hopper into a horizontal conduit for pneumatic conveyance of granular resin material therethrough, the hopper having a slide gate valve having a housing, a horizontally elongated blade therewithin, and a pneumatic piston-cylinder combination connected to the valve for blocking or permitting the granular resin material downward flow out of the hopper outlet and through a passageway in the slide gate valve according to position of the piston moving within the cylinder, the cylinder being a double ended cylinder having the piston within the cylinder in response to differential pressure on either side of the piston, the cylinder including first and second piston rods of common diameter extending from respective sides of the piston through ends of the cylinder; the slide gate valve being connected to the hopper and positioned below the hopper outlet, with the passageway through the slide gate valve being aligned with the hopper outlet, the slide gate valve blade being connected with one of the piston rods; the slide gate valve blade residing below the hopper outlet and being moveable horizontally responsively to the piston to regulate the size of the passageway through the slide gate, the horizontal conduit being continuously open for pneumatic conveyance of granular resin material therethrough regardless of piston position within the cylinder, the improvement comprising:
 a) a sensor connected to the hopper for detecting level of granular resin material therein; 
 b) control valves in the cylinder, one control valve on either side of the piston, for relieving pressurized fluid out of the cylinder from respective sides of the piston; and, 
 c) a microprocessor connected to control valves, and connected to the sensor, for regulating granular resin material flow downwardly out of the hopper outlet through the slide gate passageway by continuously positioning the piston connected to the slide gate to continuously regulate the size of the slide gate passageway by controlling differential pressure on the piston through adjustment of the control valves in response to signal from the sensor. 
 
     
     
       10. In a method for continuously supplying controlled amounts of granular resin material from a storage hopper to a pneumatic conveyance conduit having an airstream flowing therethrough for pneumatic conveyance of the granular resin material through the conduit, the hopper having a valve in a downwardly opening outlet from the storage hopper and a double ended piston-cylinder combination resident in the cylinder, a piston of the piston-cylinder combination being connected to the valve, the method including positioning the piston within the air cylinder in response to differential pressure on either side of the piston with common diameter piston rods extending from opposite sides of the piston slideably through opposite ends of the cylinder;
 the improvement comprising:
 a) moving the piston horizontally by adjusting differential pressure on either side of the piston until the piston reaches a position resulting in the desired flow rate of granular resin material downwardly out of the hopper into the pneumatic conveyance conduit; and 
 b) continuously regulating downward flow of granular resin material out of the hopper into the horizontal pneumatic conveyance conduit through adjusting position of the piston by adjusting differential pressures on the piston in response to at least one feedback signal indicative of status of granular resin material flow out of the hopper. 
 
 
     
     
       11. In a method for continuously supplying controlled amounts of granular resin material from a storage hopper to a pneumatic conveyance conduit having an airstream flowing therethrough for pneumatic conveyance of the granular resin material through the conduit, the hopper having a valve in a downwardly opening outlet from the storage hopper and a double ended piston-cylinder combination resident in the cylinder, a piston of the piston-cylinder combination being connected to the valve, the method including positioning the piston within the air cylinder in response to differential pressure on either side of the piston with common diameter piston rods extending from opposite sides of the piston slideably through opposite ends of the cylinder;
 the improvement comprising:
 a) moving the piston horizontally by adjusting differential pressure on the piston until the piston reaches a position resulting in the desired flow rate of granular resin material downwardly out of the hopper into the horizontal pneumatic conveyance conduit; and 
 b) regulating downward flow of granular resin material out of the hopper into the pneumatic conveyance conduit through adjusting position of the piston by adjusting differential pressures on the piston in response to at least one signal indicative of status of granular resin material conveyance in the conduit. 
 
 
     
     
       12. The improved method of  claim 10  wherein piston position is adjusted continuously by adjusting differential pressures on at least one surface of the piston. 
     
     
       13. The improved method of  claim 10  wherein piston position is adjusted continuously by adjusting differential pressures on both surfaces of the piston. 
     
     
       14. The improved method of  claim 11  wherein piston position is adjusted by continuously adjusting differential pressures on at least one surface of the piston. 
     
     
       15. The improved method of  claim 11  wherein piston position is adjusted continuously by adjusting differential pressures on both surfaces of the piston.